mysql基础语句

1、多表查询(左连接)

SELECT a.*,b.*,b.id AS reid,c.*,c.id AS prid  FROM `1008_user` a LEFT JOIN `1008_reward` b ON a.id = b.uid LEFT JOIN `1008_prize` c ON c.id = b.rid   #外左连结

 2、夺标查询

SELECT us.*,re.*,re.id AS reid FROM `1008_reward` AS re,`1008_user` AS us WHERE re.uid = us.id   #内连结

 3关键词

select *,sum(pnum) as num from `1008_demo` group by pid order by num ASC|DESC

 函数

LOCATE(substr,str,pos)   返回子串substr在字符串str第一个出现的位置，从位置pos开始。如果substr不是在str里面，返回0。

POSITION(substr IN str)   返回子串substr在字符串str第一个出现的位置，如果substr不是在str里面，返回0.